Telescopic tube locking means



Feb. 20, 1951 H. J. WAECHTER TELESCOPIC TUBE LOCKING MEANS Filed Julyl2. 1947 INVENTOR. d/V%;.M/m

Patented Feb. 20, 1951 UNTTED STATES PATENT OFFICE 2,542,967 TELESCOPICTUBE LOCKING MEANS Harry J. Waechter, Mount Healthy, Ohio, 'assignor -toPaul Benninghofen and Eleanor C. Diesbach, Hamilton, Ohio, as trusteesApplication July l2,`1i`147,.Serial No. 7.60.621

il Claims. l

This invention relates to .telescoping tubes and is particularlydirected to a device for locking the tubes in .selected extendedpositions. An .example of the uses to which the arrangement can be putis that oi tripod legs where it is desired to vary the height of thetripod by varying the vlength of .the legs. In this use and any otheruse to which `these .telescopic tubes are adapted 'to be applied, it is.highly desirable that the locking of the .sections in .adjustedposition be accomplished Vquickly and in .the most simplied manner.

Accordingly, it `has been the object of the present inventor to provide,combination with a pair of .telescoping tubes, .a clamping .or flockingdevice which is immediately effective `orlock'ing the tubular sectionstogether when one ,section is rotated slightly .relative to the other.

It has been .a further object of the .present iinventor to provideadevice of this character which is not only easily .and .quickly 4set in.clamped ,or locked positionbut is readily released. Further, theimproved structure ,Tin its preferred .iorm incorporates an arrangementof elements which will cooperate with the smooth internal bore .oi theouter tu'be to'bring about an immediate clamping action.

Other objects relate to the structure and arrangement .of the elementswhereby `the device is easily assembled and is of extremely durableconstruction capable of withstanding hard usage.

Alnits detailed aspects the device may talre several forms. Thevprinciple in `general is to provide oppositely related conical elementswhich are drawn together upon a pliable, :flexible bushing sleeve andwhich are effective for pressing the sleeve outwardly 'as `it 'iscompressed [from the ends so 'as 'to Vmake friction'al contact `with theinternal bore of the outer tube. `One of the problems 'solved "in thisstructure vis "to provide 4an eicient 'means "for preventing common rotation of the 4tube 'section and themovable clamp- Aing member, 'that `-isto `bring about Aimmediate relative 'motion so ythat prompt andeffective clamping action follows. inventor has provided drag meanseither Vassoci- `atedwith the actuableelement orwith'the 'clampingsleeve itself which will cause these Aelements to remain stationary'relative 4to `the rotating `tube so as to produce the necessaryYclampingaction.

Other `objects and certain advantages will be more fully set `iorth `inthe description'with reference to the accompanying' drawings in which:

Figure l kisa 'sdeview of a `tripod-showing-ex- Toward this end theFigure 2 is a fragmentary sectional view taken diametrically andlongitudinally of one of the `leg structures for illustrating the deviceiorho'lding the legs in any fixed adjusted position.

Figure 3 is a sectional view taken on line 3-3 Figure 2 vfurtherillustrating the clamping or *locking device in clamping position.

Figure 4 is a view showing the outer tube section in diametrc crosssection and showing an exterior side View of the clamping device, theview showing .the device in released condi- `tion.

Figure 5 is a view taken similar to Figure 4 but illustrating a modinedform of `the device.

Figure 6 is a sectional view taken on line -B, Figure 5, detailinginparticular the rubber c'lamjping member oi the modified device.

A device .of this invention is intended :for use in any environmentwhere .telescoping tubes are utilized. It is designed 'to "hold thesetelescoping 'tubes in any adjusted position within vthe limitsprescribed by the 'lengths of the respective tubular sections. A typicalenvironment for its use is `in lthe legs of atripod. Such structure isshown in Figure 1, the upper and lower sections 'being 'indicated at I0and l1 respectively. 'The "legs support a'base member "l2 forthe cameraor whatever 'mechanism is supported on 'the tripod.

The 'upper section tu is `a plain tube with the exception that its lowerend is turned inwardly ias at 'r3 so as to have a 'snug sliding "fitwithithelower tube H. The upper tube 'is slightly larger 'than the lowertube, there 'being clearance lll between these tubes. The lower end ofthe lower tube section is 'rounded to close the same and 'to ,provide'for smooth .contact with the iioor, .the rounded endbeing indicated atI5.

`rihe 'upper end ofthe lower tube ',has .a circular plug i6 iixedthereinby means of a ,pin Tl. The pinis disposed diametrically relativeto the upper end of the tube and passes 'through that ,portion of the'plug which 4is inserted in the tube. The Aupper 'end oi the 'plug 'is`enlarged as indicated at It so as to overhang Athe Iupper end ofthetube but 'is slightly fless in 'diameter thanthe internal Jdia-meter ofthe upper tube. A tclamp Vactuating 'screw le extends axially upwardlylfrom *the plug le. As Shown 'in Figure `2, the threads of screw FS lare`relatively steep pitched. This screw i-ncludes a kcounterturned 'lowerstud portion 20 which is inserted in a\bore 2I in `the plug.. Thiscounterturned 'portion 'or stud is `also traversed by the "pin 'llholding -it in vposition"within the Iplug.

tensible orsectional 4legsfof the type `in whichithe 55 A conical thrustoribearing `member 2-2 is loosevpresent `improvement Ymay beincorporated.

ly rotatably mounted `upon `the top o'f the 4-plug 3 and has its upperend engaged by the shoulder v23 constituted by the counterturned lowerend of the screw. Specifically this element includes a base flange 24which is circular and a conical portion 25 which rises from the baseflange, its base diameter being less than the outside diameter of thebase flange. A conical element 26, identical to the one just described,is mounted on Vthe screw threads at the upper end of the screw I9. Thiselement 26 is inverted and the two elements, that is 22 and 26, arespaced apart so as to receive and engage the respective ends of aclamping bushing 21.

This clamping bushing is formed of rubber and is in the form of a plaincylinder except that its internal bore includes conical portions 28 atits upper and lower ends which engage and match with the conicalelements 22 and 25. The inter- .,nal bore or this bushing is of adiameter larger 'than that of the screw threads. Accordingly, aclearance 2% exists between the clamping bushing and the screw. A collaror flange Sil extends upwardly from the upper conical element 26, merely.being an extension thereof.

A friction element 3l is secured upon the upper `surface of the upperconical element 26. This f'friction element includes a base portion 32and a 'series of upwardlyextended spring arms 33 lying 4around its outermargin and having frictional spring urged contact with the internal boreof `the upper tube. These spring arms are concaveconvex, their convexrounded outer surfaces providing a smooth contact with the bore of theupper section. This friction element is secured into position by meansof small metal spurs 3d yformed in the bore which surrounds the collar3B.. The points of these spurs are disposed on a circumference slightlyless than that of the bore so that when the friction element isassembled fby pressing it down on top of the upper conical element, thespurs bite into the outer surface of `lthe collar and assume an inclinedposition pre- .'Venting withdrawal. Y l, IA limit screw or spacerelement 35 is screwed faxially into the upper end of rthe screw element.This element includes the usual slotted head 36, ,an intermediate bodyportion 3l and a screw I'threaded stud 3i? screwed into the axial boreof:the screw element. The body portion lits snugly within the bore of thecollar and a lock washer '[140 is inserted between the element and thetop of ".the screw element. As shown in Figure 2, there.

is suicient space between the head of this ele- "cal element to permitrotative movement and Ulongitudinal translation of the upper conicalelement in its clamping movements. r Therefore, it will be apparent whenthe lower @section is rotated so as to screw the screw threadfedelementinto the upper conicalrelement, the

lL upper conical element is drawn downwardly upon fthe clamping bushing.This action compresses the rubber element and tends to spread itradially `causing the outer surface of the rubber bushing to '.sectiontends to hold the upper conical section against rotation. However, thepressure of these ,i ment and the top of the collar of the upper coniiarms is not suicient to prevent easy longitudinal, movement. That is tosay their tension is adjusted so as' to cause a dragging action on theupper conical element. As soon as the upper conical element begins tobear down on the rubber bushing, there is added friction because of therubber and metal contact and furtherrotation is eiective for tightlyclamping the sections together.

As an alternative to the above-described structure, a modied form of thedevice is shown in Figures 5 and 6. In this form the rubber bushing isiluted as at 4l. These radially longitudinally disposed iiutes arespaced apart as shown in Figure 6 so as to permit sufficient play of theutes for creating wedging actions. These flutes are formed by millingcircular slots longitudinally in the'side wall oi' the bushing (Figure5). They do not extend entirely to the upper and lower limits of thebushing but solid portions remain to provide the requisite body for thebushing. In the rst form the rubber bushing is slightly spaced from theinternal wall of the upper element. Y

In the. instance of this Ymodilication the rubber bushing is slightlybarrel-shaped so that its larger central portion will continuouslyengage the internal wall of the upper section. This engagement providessuiicient frictional contact to provide a drag so that the bushing willnot rotate when the lower section is rotated. Since the upper conicalelement will always normally lie against its conical mating surface ofthe bushing, the rubberbushing will act as a means for holding the upperVconical element stationary when the lower section is rotated. Thus,relative motion between the screw element and the conical element willoccur and the bushing will be clamped and squeezed between the conicalmembers to produce the clamping action. In operating the device of themodification, sudden rotations of the lower section result in a quickerclamping action for they tend to prevent clinging of the upper conicalelement to the threads of the screw. If the lower section is rotated'slowly the upper conical element might tend to cling to the screw and,despite some contact with the rubber bushing, might tend to rotate withit momentarily. p

Having described my invention, I claim:

1. For use with a pair of telescoping tubesa device for locking thetubes in adjusted telescoped positions comprising; a rubber sleevemounted on the end of the internally disposed tube and adapted to gripthe internal wall of the outer tube, said rubber sleeve including aYconical bore portion at one end of its internal bore, a conicalactuating member tted into said conical `bore portion, a screw Vmemberloosely traversing tinuously exerting a frictional drag on the conicalmember relative to the internal bore of the .outer tube so that uponrotation of the internal tube and adapted to grip the internal wall ofthe outer tube, said rubber sleevegincluding conical bore portions atthe respective ends of its internal bore, conical actuating membersrespectively tted into said conical bore portions, a screw memberloosely traversing the bore of the sleeve and being screw threadedthrough one of the conical members whereby rotation of the internal tubein one direction will compress the rubber sleeve and outwardly expandthe same f against the internal bore of the outer tube and rotation inthe other direction will release said sleeve from said compressivepressure and, means for continuously exerting a frictional drag on saidlatter conical member relative to the internal bore of the outer tube sothat upon rotation of the internal tube relative motion will occurbetween the screw and the conical member.

3. A device for locking a pair of telescoped tubes in various positionsof axial adjustment relative to each other comprising; a screw memberaxially projected from the inwardly disposed end of the internal tube, aconical member screw threaded on the threads of the screw, a rubberbushing surrounding the screw, said bushing including a flared internalbore portion at the end thereof mating with the conical portion of theconical member whereby rotation of the internal tube and the screwrelative to the outer conical member causes compressing of the bushingand outward pressure of the bushing against the internal bore of theouter tube, said bushing including longitudinally externally disposedflutes whereby the engagement of the utes with the internal wall of theouter tube will tend to prevent rotation of the bushing and engagementof the bushing with the conical member will provide a drag forpreventing rotation of the conical member with the screw.

4. A device for locking a pair of telescoped tubes in various positionsof axial adjustment relative to each other comprising; a screw memberaxially projected from the inwardly disposed end of the internal tube, aconical member loosely rotatably mounted on said screw adjacent the endof the internal tube, a second conical member screw threaded on thethreads of the screw in a position spaced from the first-named conicalmember, the conical portions of the members facing each other, a rubberbushing surrounding the screw and disposed between the conical members,said bushing including flared internal bore portions at the respectiveends thereof mating with the conical portions of the conical memberswhereby rotation of the internal tube and the screw relative to thescrew threaded conical member causes compressing of the bushing betweenthe conical members and outward pressure of the bushing against theinternal bore of the outer tube, said bushing including longitudinallyexternally disposed utes and the bushing being barrel-shaped in externalcontour whereby the engagement of the utes with the internal wall of theouter tube will tend to prevent rotation of the bushing and engagementof the bushing with the screw threaded conical member will provide adrag for preventing rotation of this conical member with the screw.

HARRY J. WAECl-ITER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 663,804 Buder Dec. l1, 19002,019,753 Wittel Nov. 5, 1935 2,374,947 Nicholson May 1, 1945 FOREIGNPATENTS Number Country Date 530,320 Germany Mar. 18, 1930 '718,486France Nov. 4, 1931

